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Once or twice a week taskhost.exe slows my computer to a halt! It takes up 25% of my CPU power (ie. 1 processor). I can't kill it an have no idea what it is doing. I imagine that its some kind of window's scheduled activity.

How can I figure out what is causing this problem? How can I stop it?

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TaskHost.exe itself is a wrapper for dll or other exe and run as a windows service.

3 things to try


Before spending time hunting down what taskhost actual loaded. Check Event Viewer for errors. That may give out a quick answer or point you to the right direction.


Open Task Manager, go to Processes tab. On menu bar (top), click View -> Select Columns.... In pop-up windows, select Command Line.

That may give you an idea which dll taskhost.exe loaded.

Additionally, pay attention at the path of taskhost.exe. It should be

<Windows directory>\System32\Taskhost.exe

If not, you may have other problem.


Same idea as #2, but use a better tools. Download Process Explorer from Microsoft. It is free. It is able to give more details of running process.

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The path of taskhost.exe is simply: "taskhost.exe $(Arg0)". I've downloaded and run the latest Microsoft Security Essentials and it detected no viruses. – user145395 Nov 14 '12 at 22:15
What windows version are you running? Do apply all patches from MS? – John Siu Nov 15 '12 at 3:06
Yes system is up to date. I actually just figured this out finally. About to post an answer. – user145395 Nov 15 '12 at 19:51
#2 is extremely useful, thanks. I am using Windows 8, it's a little different there - open task manager, tab 'Processes', right click on the column headers, then check the command line column. – Martin Hansen Sep 7 '14 at 12:23

Turns out this was caused by the "RacTask" (Reliability Analysis Custom Handler). I used the Task Scheduler to view "All Running Tasks" and then killed it from there. The problem was immediately addressed.

The suggestion to try this was taken from this thread...

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Very nice to see solution feed back! Learn something new. – John Siu Nov 15 '12 at 21:53
So how did you find out what task it was? What method did you use? – Martin Hansen Sep 7 '14 at 12:21

I checked with our system support team and told to do the following :

  1. Start -> run -> %temp% delete all files and folders
  2. Start -> run -> prefetch same as above
  3. Remove all files and folders from recycle bin
  4. Restart the computer
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Killing via Task Manager kills it only once.

If you want to disable it permanently, see

In my case, the task seemed to have something to do with Microsoft Customer Experience Improvement Program. (Ironic). It seems to me it was connected in someway with uploading customer configuration data to Microsoft. If so, seems harmless to disable.

Summary: run taskschd.msc, locate Microsoft/Windows/RAC, disable it using GUI.

+1 to the tip to download Process Explorer

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Could whoever downvoted my reply explain to me what prompted it? Was my advice wrong? – Jim Davis Jun 19 '15 at 19:35

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